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Ethiopian wolves in danger

Ethiopia’s last wolves threatened by lack of genetic diversity as populations become isolated

Genetic structure and patterns of gene flow among populations of the endangered Ethiopian wolf

October 2102. Populations of endangered mammals are often small, fragmented and have low genetic variability that can reduce the ability to evolve in response to environmental changes.

6 small & isolated populations

The endangered Ethiopian wolf (Canis simensis) is a habitat specialist restricted to six small, isolated pockets of Afroalpine habitat, with a total population of fewer than 500 adult animals. The degradation of the Ethiopian highlands because of human expansion is ever increasing, potentially leading to further population fragmentation and local extinctions.

In order to assist Ethiopian wolf conservation management, researchers from ZSL quantified the genetic diversity, population structure and patterns of gene flow of the species and other analyses that revealed geographic a population structure delimited by three mountain ranges, in concert with a previous study based on mitochondrial DNA.

Further analysis showed that current gene flow is low, unidirectional and limited to geographically proximate populations. Given the small census size and strong population structuring with low gene flow, demographic stochasticity (population fluctuations due to random demographic events) is likely to be the highest threat to the long-term persistence of this species.

Habitat protection is vital

The protection of the remaining suitable habitat, especially narrow ridges linking habitat patches within mountain blocks, is therefore essential. The genetic survey presented by this study provides vital and much needed information for the future effective management of Ethiopian wolf populations.

Ethiopian wolf history

The Ethiopian wolf, Canis simensis, is a medium-sized canid highly adapted to life in Afroalpine ecosystems above altitudes of 3000 m, where it preys almost exclusively on high altitude rodents. This highly specialized canid diverged from its wolf-like ancestor about 100,000 years ago, at the peak of the last glaciation, when Afroalpine habitat reached its maximum expansion allowing the wolves to colonize the Ethiopian highlands.

It is likely that the Ethiopian wolf exhibited its largest range and most continuous distribution during this period. Numbers began to decline with the onset of the present interglacial, 18,000 years ago, as Afroalpine habitats started to disappear from lower altitudes replaced by montane forests. Suitable habitat became increasingly fragmented, forcing the wolves to retreat into the remaining mountain refugia.

These persistent threats indicate that in the future it might be necessary to manage Ethiopian wolf populations by artificially increasing population size and genetic diversity.

Restoring gene flow could reinforce population size, decrease inbreeding, possibly induce heterosis (Opposite of inbreeding), decrease the extent of random genetic drift because of small population size in population fragments and increase genetic variability and adaptive potential.

Population management

Attempts to restore gene flow when the isolation is the result of a natural process can be controversial. This is particularly relevant for species like the Ethiopian wolf with a current population structure shaped by postglacial climatic changes. Management of populations to restore gene flow could have detrimental effects if local adaptation is strong, by importing ill-adapted alleles(gene groups) and diluting adapted gene pools.

Therefore, the construction of a balanced in situ management programme that maintains historic levels of variation within and gene flow among Ethiopian wolf populations requires identifying population boundaries and investigating patterns of gene flow among these populations. Its recent speciation and relatively simple life history, makes the Ethiopian wolf an ideal system to evaluate the power of genetic-marker-based inferences and the suitability of these inferences for species with more uncertain evolutionary histories.

Research

This research was undertaken by Dada Gotelli of the Institute of Zoology, Zoological Society of London, London, UK, and others from The Wildlife Conservation Research Unit, Zoology Department, University of Oxford, Tubney, UK, and Nature Heritage, Berlin, Germany.